// Deployment-wide settings: K/V backed by D1, with a short-TTL KV cache so
// hot paths don't hit D1 on every request. Used by the update flow to store
// the owner's CF API token + related metadata, and reserved for future
// deployment-wide config (branding, telemetry retention, etc.).

import type { Env } from '../../env';

const KV_PREFIX = 'settings:';
const KV_TTL_SECONDS = 300;

// Cache "no value set" as well, so missing keys don't hammer D1 either. KV
// can't store null, so we use a sentinel string the caller will never produce.
const TOMBSTONE = ' ';

export async function getSetting(env: Env, key: string): Promise<string | null> {
  const cacheKey = KV_PREFIX + key;

  try {
    const cached = await env.KV.get(cacheKey);
    if (cached === TOMBSTONE) return null;
    if (cached !== null) return cached;
  } catch {
    // KV failures should not break request handling — fall through to D1.
  }

  let value: string | null = null;
  try {
    const row = await env.DB
      .prepare(`SELECT value FROM deployment_settings WHERE key = ?`)
      .bind(key)
      .first<{ value: string }>();
    value = row?.value ?? null;
  } catch {
    // Table may not exist yet on a brand-new deploy that hasn't bootstrapped.
    return null;
  }

  try {
    await env.KV.put(cacheKey, value ?? TOMBSTONE, { expirationTtl: KV_TTL_SECONDS });
  } catch { /* best-effort */ }

  return value;
}

export async function setSetting(env: Env, key: string, value: string | null): Promise<void> {
  const now = Math.floor(Date.now() / 1000);

  if (value === null) {
    await env.DB
      .prepare(`DELETE FROM deployment_settings WHERE key = ?`)
      .bind(key)
      .run();
  } else {
    await env.DB
      .prepare(
        `INSERT INTO deployment_settings (key, value, updated_at) VALUES (?, ?, ?)
         ON CONFLICT(key) DO UPDATE SET value = excluded.value, updated_at = excluded.updated_at`
      )
      .bind(key, value, now)
      .run();
  }

  // Bust the cache so the next read picks up the new value immediately.
  try { await env.KV.delete(KV_PREFIX + key); } catch { /* best-effort */ }
}